The president has had major problems trying to fill the power vacuum, with parties refusing to form a government.

Mr Raikov, who will also be foreign minister, said Bulgaria's currency would continue to shadow the euro and the current budget would stay in place, but there would be help for the poor.

Analysis

By Nick ThorpeBBC News, Sofia

Marin Raikov, the new Bulgarian prime minister, has been recalled from his job as Bulgaria's ambassador to Paris to run the interim government. Aged 52, a career diplomat, he has also served twice as deputy foreign minister.

"The new prime minister will have three main tasks," says Daniel Smilov, of the Centre for Liberal Strategies in Sofia. "To ensure financial stability, to prepare May elections, and try to win back the confidence of the Bulgarian people in the institutions of state."

President Rosen Plevneliev struggled for three weeks to find candidates willing to take the post, after the surprise resignation of Prime Minister Boyko Borisov and his Citizens for the European Development of Bulgaria government on 20 February.

The main political parties refused to participate in the caretaker government, as they prepare for the elections. Some potential candidates said they feared the the elections would be indecisive, and that the caretaker government would have to stay on for new elections to be called.

He told reporters: "While we follow strictly the 2013 budget framework, we will take steps to improve the incomes of pensioners and the poorest."

Deputy Central Bank Governor Kalin Hristov was named as the new finance minister.

Bulgaria joined the European Union in 2007 but is its poorest member. Bulgarians had hoped EU membership would see prosperity rising,

But a quarter of the country's population still lives below the poverty line, with incomes half that of the European average.

Anger had also grown with the previous government over a perceived failure to tackle cronyism and corruption.

Winter electricity bills have risen sharply - for some they are higher than the monthly wage.

The death of at least two protesters by self-immolation fuelled public anger.

After more than a week of protests, former Prime Minister Borisov tried to calm the protests by promising to slash electricity prices and by sacking his finance minister.